The First Amendment

The first amendment (part of the Bill of Rights) reads:

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.

The first two clauses are known as the establishment clause and free exercise clause, respectively. Together, they define the wall of separation between church and state that Thomas Jefferson wrote of.

The Supreme Court has interpreted the establishment clause as meaning that the government may not favor one religion over another, or favor religion in general over no religion (or vice-versa). In other words, the government must remain strictly neutral in matters of religion.

At the same time, the free exercise clause guarantees freedom of religion. A proper balance between these two clauses can sometimes be hard to find.

In the 1971 case Lemon v. Kurtzman, the Supreme Court established the Lemon test for determining whether a law violates the establishment clause: a law is legal if:

It has a legitimate secular purpose, and

Its principal effect neither advances nor inhibits religion, and

It does not foster an excessive government entanglement with religion.